Ethylene flow

The feed stream to a reactor contains ethylene 16 per cent, oxygen 9 per cent, nitrogen 31 per cent, and hydrogen chloride. If the ethylene flow is 5000 kg/h, calculate the individual component flows and the total stream flow. All percentages are by weight. 

The flow of any component in Example 2.6 could have been calculated directly from the ratio of the percentage to that of ethylene, and the ethylene flow. 

The checkers found that best results were obtained when the slowest detectable nitrogen flow was used with a fairly rapid ethylene flow (about 1 in. of foam in the gas washing bottle at the reaction temperature). 

Slight improvements in sensitivity can be achieved by cooling the phototubes used to detect the emitted light or by increasing the ethylene flow rate. Chemiluminescence produced by the reaction of ozone with ethylene has been designated by the epa as the reference method for monitoring ozone. Several different commercially produced instru< ments are available. 

During this operation the mixture is stirred continuously and the ethylene flow is maintained through the flask and the neck, so preventing the ingress of air. 

Fig. 4-5. Yields of HCN and 14N15N from the reaction of active nitrogen with 15NO-C2H4 mixtures ranging in composition from pure C2H4 to pure 15NO. The symbols ( ) and (O) represent experiments in which the ethylene flow rate was maintained at values in excess of titration end point while increasing increments of nitric oxide were added. The symbols ( ) and ( ) correspond to experiments in which nitric oxide flow rates were held at values in excess of titration end point while various amounts of ethylene were added (from Fersht and Back139 with permission of the National Research Council of Canada).

Fig. 8.12 Setup for photoacoustic free-field measurement. The diagram shows a real signal of voltage versus time when 2% ethylene flowed through all channels (reproduced by permission ofWiley-VCH, Weinheim from [24]).

Increasing the reactor temperature setpoint increases the production rate of vinyl acetate, so there must ultimately be net increases in all three fresh reactant feed streams. Oxygen and ethylene flows respond fairly quickly within about 20 minutes. However, the acetic acid feed actually decreases for the first 60 minutes in response to an increase in column base level. These results demonstrate the slow dynamics of the liquid recycle loop and illustrate the need for controlling the total acetic acid flow to the reactor so that the separation section does not see these large swings in load ( snowball effect"). The variability is absorbed by the fresh feed makeup stream. 

The ethylene and polyethylene leave the reactor and pass into a primary separation vessel which operates at a much lower pressure than the reactor itself. Most of the ethylene (and any comonomer) is flashed off in this unit and recycled through compressors to the tube inlet. Conversion per pass is of the order of 30% with ethylene flow rates about 40,000 kg/h. 

Figure 20.24 Effect of reactor configurations (refer to Figure 20.23 for eonfigurations) on the distribution of film thiekness on the electrode bell jar type of reaetor in the flow direction 2torr lOOW ethylene flow rate 80 seem 60 min. Adapted from Ref. 4.

On one occasion when ethylene was added at a higher rate, the reaction proceeded with a flame which extinguished itself as soon as the ethylene flow was stopped. A total of 0.179 gram of ethylene was added to 1.3 grams of O2CIF3 the temperature of the bath after this addition was slowly raised at the rate of 1° to 15° per minute. No gas evolution was noticed up to 140° K. At 140° K. a violent explosion took place, shattering the reaction vessel and a large part of the reaction system. Evidently, intermediate or partly oxidized products were formed. 

Ethylene production by steam cracking of ethane Eonr cases with two or three objectives from (1) maximization of ethane conversion, (2) maximization of ethylene selectivity, and (3) maximization of ethylene flow rate. NSGA-n Reactor inlet temperatnre and length were observed to be the most important decision variables. Tarafder et al. (2005b)... 

The gradual decay with time in the polymerization rate characteristic of Cr/aluminophosphate is different from that of Cr/silica. It has sometimes been attributed to mass transport limitations caused by polymer buildup around the active sites. To test this hypothesis, a stopped-flow experiment was conducted, as represented in Figure 170. In this run, the polymerization rate with Cr/AIPO4 was allowed to build up to its highest value, which occurred in 10 min. Then the ethylene flow was stopped, and the reactor was depressurized to remove residual ethylene. After about 75 min, the ethylene was readmitted and polymerization continued. However, it continued not at the rate at which it had left off,... 

Fig. 4.11 The absorbance spectra of CO2 measured at the outlet of a CSTR, operated with ethylene at 2000 bar, 50°C, and a mass flow of 3 kg h after Injecting (at f = 0) a tracer of CO2 into the ethylene flow just before entry to the CSTR.

The two correlations are in reasonable agreement, and show that the flaoding velocity is over twice the calculated gas velocity based on ethylene flow to the vessel. Based on the lower value of... 

A conventional flow-type reaction system was used for reactions at atmospheric pressure. The liquid sample was vaporized at 0 C with the aid of nitrogen and ethylene flows, and the resulting mixtures then entered the reactor. The reactor was an annular quartz cylinder of 200 mm length and 10.6 mm i.d., equipped coaxially with a thermowell of 7.2 mm o.d. The reactor was positioned in an electrically heated brass block of 180 mm length,... 

A typical fluidized bed reactor has a length-to-diameter ratio of ca 7 and a disengagement zone at the top. Uniform fluidization is achieved by ethylene flow through a distribution plate at the reactor bottom, and rapid circulation is needed to remove heat. Conversion is about 2% per pass. Unreacted ethylene enters the disengagement zone, separates from the entrained polymer particles, and is Altered, cooled, compressed, and recycled. A catalyst is continuously fed to the reactor without diluent, and polymer particles are continuously removed from the bed through a system of valves. Reactor temperatures of 70-100°C are common, with pressure of 1.4-3.5 MPa (200-500 psig). 

The pressure of the gas loop can be controlled by the ethylene flow, the oxygen flow or the pressure of the recycled HCl stream. And sinee the oxygen flow has been previously selected and the composition of both oxygen and ethylene is very small in the recycled HCl stream, the pressure of the gas loop controlled consequently by controlling the top pressure of the HCl recovery column. 

Figure 3.9 Ethylene polymerization rates for chromium on silica (o) and for chromium/ titanium on silica (square symbol). Ethylene flow rate in arbitrary imits per gram of catalyst. Reprinted from [11] with permission from John Wiley and Sons.

Each type of support was evaluated in a 2.2-liter stainless steel autoclave fitted with a temperature control jacket and a marine stirrer. Each supported, finished catalyst was prepared in situ by sequentially adding to the polymerization reactor 10-100 mg of finished support, 2.0 ml of a toluene solution containing 0.5 wt% (n-butyCpj ZrCl, 0.6 liter of isobutane, 1.0 mmol triethylaluminum and a second addition of 0.6 liter of isobutane. The contents of the reactor were stirred at 400 rpm while the reactor was heated to 90°C, after which ethylene was added to the reactor system to maintain total pressure at 550 psig. After the polymerization experiment, the ethylene flow to the reactor was stopped, the reactor was cooled to ambient temperature and solvents were removed by evaporation, and the reactor was opened and the polymer was collected. Note that no reactor fouling was detected and the granular polyethylene had acceptable morphology important for a commercial process. 

Dynamic contact angle measurement indicated that the surfaces of flax fibers treated with ethylene plasma exhibited greater water contact angle than the untreated and the acetylated flax, reflecting that the plasma-treated flax surfaces became more hydrophobic [122]. The contact angle was increased on increasing the ethylene flow rate to 0.5 cm s and the plasma power to 50 W. 

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